When influencing the flow behavior of fluids flowing around a flow body, such as the aerofoil of an aircraft, for example, active flow influencing by actuators is known in the art, and can be achieved by generating what are known as “synthetic jets”. This name is based on the fact that the relevant actuators do not require any external fluid supply as the time-averaged net mass flux is zero, whereas the fluid momentum is not equal to zero. In this case, a flow body can be understood to mean any external aircraft parts that are exposed to a fluid flow.
For example, in the aviation field, the synthetic jets are researched and used to improve noise behavior, to improve flow behavior on the surface of the flow body in question, in other words, the aerofoil, for example, and to improve lift and manoeuvrability. In this connection, the central issue often concerns dynamic lift as the variable that keeps an aircraft in the air and the extent to which parameters such as size, weight, forces and complexity of flow control each influence flight behavior.
A synthetic jet flow can be generated in various ways in such a situation, for example, by an electromagnetic, mechanical and thermal drive force, which causes a membrane to be moved in the desired manner in each case, as a result of which the surrounding fluid is drawn into the cavity and then ejected again. The components used in such cases should be designed to be correspondingly compact and robust.
An actuator assembly of this type is known in the art from U.S. Pat. No. 9,073,628 B2, for example. However, in the actuator assembly illustrated in this document, the design of the actuator assembly and the design of the opening through which some of the fluid volume flows into or out of the cavity mean that both thermal problems and flow losses may arise if excitation of the actuator is subject to reasonable mechanical amplification. Furthermore, problems may arise with this assembly or a similar assembly as a result of excitation of undesirable vibration modes.